In many modern industrial settings, modular conveyor systems are extensively utilized for transporting articles to and from various work stations during all stages of production. During the past several years, manufacturers and producers using production lines with modular conveyors as an integral component of the material handling system have realized reasonably significant gains in productivity and resource utilization. Accordingly, modular conveyor systems have become even more widely adopted in the industry, and have been adapted to meet an even wider scope of the material handling needs of producers of a multitude of consumer and industrial products, especially in the food processing sector.
Notwithstanding recent developments and advancements in modular conveyor system design, further improvements in material handling efficiency are desired. For example, because of the nature of the standard conveyor drivers utilized in modular conveyor systems developed to date, the entire surface area of a conveyor belt cannot be used as an uninterrupted conveying surface. Specifically, designers of most prior art conveyor systems have not been able to develop and implement a commercially successful endless material handling conveyor loop that requires no inverted return run. In essence, none of the successful prior art systems provide a conveyor system having the capability of utilizing more than roughly half of the available conveying surface at any given time during operation.
In order to provide the requisite driving force to a conveyor belt, most prior art modular conveyor system drive means include some form of sprocket driving assembly. One example of a conveyor driving system of this type is disclosed in the expired U.S. Pat. No. 3,724,285 to Lapeyre. A later U.S. Pat. No. 4,953,693 to Draebel, owned by the assignee of the present invention, illustrates a significant advance in the structure of the modular conveyor components of this type of conveyor system. However the Draebel '693 patent retains the typical conveyor drive system; i.e. one or more driving sprockets mounted on a drive shaft at one end and an idler sprocket and shaft at the other end. As clearly shown in FIG. 11, this arrangement still suffers the disadvantage of requiring an inverted return run of the conveyor, thus rendering approximately one-half of the conveyor structure unusable at any given time. This not only increases the cost involved in such a conveyor system, but also significantly increases the power required to drive the conveyor system.
There are several other key disadvantages that have been realized with regard to having to provide a such a return run. Specifically, it is not uncommon in the prior art to have to mount the frame for the return run separately from the main conveyor frame that supports the forward or operative run of the belt. This further increases the complexity of the design and also significantly adds to the conveyor system's initial construction costs, as well as the installation cost and later maintenance expenses.
Another key disadvantage of the forward and return feed arrangement is the requirement to provide separate transfer zones to couple two or more conveyors together to make a complete run, such as a full endless conveyor loop. This requires special design of transfer plates, including in many instances idlers or powered transfer rollers. Again a significant additional expense is represented. Furthermore, these transfer zones simply do not work very well, sometimes causing articles, such as soft packages or food products, being transported to hang up or even jam, thus causing a shutdown of the entire system. Even when working properly, there can be a tendency for such articles being transported to backup at the end of the forward run as the articles temporarily slow as they negotiate the transition.
Thus, it is clear that a need exists for a conveyor system with improved material handling capabilities that includes an endless horizontal loop conveyor belt providing an uninterrupted conveying surface and requiring no return run. Such a conveyor system would not need transfer zones with plates and rollers, and would not experience resultant end-of-conveyor slow down of articles, and associated article backup. Such a conveyor system would be capable of transporting articles along an uninterrupted continuous flow path. The system would also be capable of being sufficiently flexible to accommodate the transportation of articles of different hardness, textures, sizes and/or shapes. Further, such a conveyor system would be able to provide for the transport of articles in an economically more efficient, smoother, more productive and more reliable manner.
An example of where an endless loop conveyor system would prove useful is in the food processing industry, and more particularly in the poultry industry. Poultry products are processed, packaged in trays and/or wrapped in assembly line fashion at stations spaced around the loop.